Global Atmospheric Circulation and Tropical Storms

Global Atmospheric Circulation

The large-scale movement of air. Helps to explain the distribution and location of the world's climate zones and weather hazards.

Isolation

The amount of solar radiation (sunlight) an area receives.

Equatorial Region

The region where the Sun's rays strike the surface more directly, concentrating solar radiation over a smaller area, resulting in more intense heat.

High Latitudes

Regions where the Sun's rays strike the Earth at an angle, spreading solar radiation over a larger area, leading to lower temperatures.

Coriolis Effect

The way Earth's rotation causes moving air and water to turn instead of moving in a straight line; in the Northern Hemisphere, things curve to the right, and in the Southern Hemisphere, they curve to the left.

Convection Cell

Areas where warm material is rising and cold material is sinking.

Hadley Cells

A large atmospheric circulation cell found between the equator and 30° latitude, where warm air rises at the equator creating tropical rainforests and sinks at 30° forming deserts like the Sahara.

Ferrel Cells

The cell that lies between 30° and 60° latitude, where air rises around 60° creating temperate forests or grasslands and sinks at 30° overlapping with desert regions.

Polar Cells

The cell that operates between 60° and the poles, where cold air sinks at the poles forming polar deserts and rises at 60° supporting tundra or boreal forests.

Natural Hazard

A natural event that has the potential to cause death, damage and destruction.

Hurricanes

Tropical storms that occur in the Atlantic and Eastern Pacific Oceans.

Typhoons

Tropical storms that occur west of the North Pacific Oceans.

Cyclones

Tropical storms that occur in the Indian and South Pacific Oceans.

Distribution of Tropical Storms

Tropical storms most commonly occur between 5° and 20° latitude, both north and south of the equator, where warm ocean waters and favorable atmospheric conditions support storm formation.

'Ingredients' Needed for a Tropical Storm to Form

Sea Temperatures (27) + deep water = provides heat and moisture; Not along the Equator = Coriolis effect is not strong enough; Low Wind Shear = storm clouds can rise to high levels without being torn apart.

How a Tropical Storm Forms

Sun sends incoming solar radiation (insolation) - heating oceans to critical 27. Air above the oceans is heated. Warm, moist air rises through the air as thermals = low pressure. Air cools as it rises - causes condensation to occur, cumulonimbus clouds to form and torrential rain to fall. Some cooled air sinks down, creating the eye; conditions here are dry and calm. Coriolis Effect causes air to spin upwards around the eye, counterclockwise NH, clockwise SH. Storm travels across the ocean in the prevailing wind. When the storm meets land - loses power and weakness as they are no longer fueled by the source of moisture and heat (ocean) - friction also slows storms down.

EYE

calm, clear, area of sinking air and light winds that don't exceed 15mph. 32-64km across. Develops when the maximum sustained speed goes above 74mph.

EYEWALL

eye can grow or shrink in size - consists of a wall of tall thunderstorms that produce heavy rains and the strongest winds.

RAINBANDS

curved bands of clouds and thunderstorms that trail away from the eye wall in a spiral fashion. Produce heavy rain and wind.

Primary Effects

Strong Winds. Torrential Rainfall. Storm Surges.

Secondary Effects

Flooding. Landslides. Contaminated water sources.

Saffir-Simpson Hurricane Wind Scale

75-95 - very dangerous - some damage. 155+ - Catastrophic damage.

Immediate Responses

Evacuation. Shelter. Distribution of emergency food and water.

Long-term Responses

Repairing damage. Investing in methods of prediction and planning. Sustainable Development.